1. Field of the Invention
This invention relates to a photographic camera, and, more particularly, to a photographic still camera equipped with a magnetic head for magnetically recording data in a magnetic data recording track of a film strip.
2. Description of Related Art
In what is called an advanced photographic system (APS) including a new type of films which has been recently announced, cameras pertinently prepared to the new system are equipped with magnetic heads for entering and recording required data including exposure data, such as shutter speeds, exposure apertures and the use of artificial light, and selected data regarding exposed frames according to the photographer's intention in a magnetic data recording track. These required and selected data are read and used as input data by a printer for proper exposure control. The film strip available for the new system has a transparent magnetic layer coated on one side of a base substrate opposed to the side of emulsion layer. Such a camera pertinently prepared to the new system is provided with a magnetic head installed to, for instance, a pressure plate behind an exposure aperture frame so as to contact with the transparent magnetic layer of the film strip. The magnetic head is driven for data recording in the recording track of the film strip whenever the film strip is advanced after exposure of each image frame.
In order for the magnetic head to perform proper magnetic recording, proper contact of the magnetic head with the magnetic layer must be always provided. As is well known in the art, the magnetic head, in particular the magnetic head surface, rubs the magnetic layer and produces film shavings which cling on the magnetic head surface we well as ambient dust. These shavings and dust having clung to the magnetic head surface develop a slight gap and/or yield non uniformity of contact between the magnetic head surface and the magnetic layer. Such a lack of the uniformity of contact and a gap cause deterioration of frequency characteristics and aggravation of the intensity of magnetization of the magnetic layer which are always undesirable for proper magnetic recording.
Foreign materials or dust clung to the magnetic head surface during film advancement shave the magnetic layer with a result of destroying or losing recorded data and/or with the effect of lowering the intensity of magnetization of the recorded data. Film strips have experienced such aggravation of magnetic characteristics. Data read from such a film strip and used as input data by a printer encounters degradation in signal level, resulting in poor or improper data reproduction and inadequate exposure and printing control. In order to eliminate these particles, the magnetic head surface may be periodically cleaned directly with a piece of cloth infiltrated with alcohol.
While the utilization of alcohol infiltrated cloth is effective in removing dust and shavings having clung to the magnetic head surface, nevertheless, various constraints must be imposed on cleaning work. In addition, the cleaning work is somewhat technically troublesome and is unpractical for ordinary photographers. For instance, a drop-in loading type of camera which has only a narrow opening for access to the camera interior requires the photographer to remove its back lid in order to obtain access to the magnetic head and clean it. It is, however, almost impossible for ordinary photographers to remove the back lid from the camera.